The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Engines produce torque by burning a fuel to create engine, and discharge surplus thermal energy. Particularly, a coolant absorbs thermal energy as it circulates through an engine, a heater, and a radiator, and releases the thermal energy.
Oil becomes highly viscous at low engine coolant temperatures. With thick oil, friction and fuel consumption increase, and exhaust gas temperatures rise gradually, lengthening the time taken for catalyst activation and causing deterioration in exhaust gas quality. Moreover, it takes a long time to get a heater to function normally, so passengers and a driver will feel cold.
When the engine coolant temperature is excessively high, knocking may occur. If ignition timing is adjusted to suppress knocking, the engine performance may be degraded. In addition, excessive lubricant temperatures may result in poor lubrication.
However, one coolant control valve is used in specific regions of an engine, and is a valve that controls a number of cooling elements, like keeping the coolant at high temperatures and other regions at low temperatures.
On the other hand, the coolant of the cylinder block of the relatively low temperature is supplied to the oil cooler and the EGR cooler in a warm condition of the temperature of the coolant such that the fuel consumption may be increased due to the decreasing of the oil temperature and the temperature of the EGR cooler may be overcooled, or the coolant of the cylinder head of the relatively high temperature is supplied to the oil cooler and the EGR cooler such that the oil temperature may be overheated and the temperature of the EGR cooler may be overheated in a high temperature condition of the coolant.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.